Poly(phenylene ether)s are a class of plastics known for excellent water resistance, dimensional stability, and inherent flame retardancy, as well as high oxygen permeability and oxygen/nitrogen selectivity. Properties such as strength, stiffness, chemical resistance, and heat resistance can be tailored by blending poly(phenylene ether)s with various other plastics in order to meet the requirements of a wide variety of consumer products, for example, plumbing fixtures, electrical boxes, automotive parts, and insulation for wire and cable.
Blends of poly(phenylene ether)s and polystyrenes are commercially available and used for injection molding articles such as housings for appliances and consumer electronics. To reduce waste and conserve energy, it would be desirable to prepare blends of poly(phenylene ether)s and polystyrenes using recycled polystyrene materials. U.S. Pat. No. 5,264,487 to Scobbo et al. describes a plastic composition that includes a poly(phenylene ether) and a polystyrene, and further includes an acrylonitrile-butadiene-styrene copolymer and a copolymer of an olefin such as ethylene and an epoxy compound such as glycidyl methacrylate. The poly(phenylene ether), polystyrene, and acrylonitrile-butadiene-styrene copolymer can be provided in the form of a mixed recycling stream. However, the poor compatibility of the acrylonitrile-butadiene-styrene copolymer with the poly(phenylene ether) and polystyrene requires the use of the olefin-epoxy copolymer as a compatibilizer. It would be desirable to avoid the complexity and expense of using such a compatibilizer.
U.S. Pat. No. 7,964,675 to Ko et al. describes a plastic composition that includes a recycled poly(phenylene ether) and another recycled plastic that can be, among others, acrylonitrile-butadiene-styrene copolymer. The composition minimizes or eliminates any recycled plastic that can decompose and form volatile components during formation of the plastic composition. The Ko composition maximizes use of recycled feedstocks, however, its impact strength is not sufficient for some injection molding applications.
There remains a need for blends of poly(phenylene ether)s and polystyrenes that utilize a recycled plastic feedstock while largely preserving the impact strength exhibited by blends prepared from virgin resins.